Spectral and Kinetic Study of 3-Styrylquinoxalin-2(1H)-ones Photoreduced by N-Phenylglycine and Amines

Díaz-Hernández, Dafne; Cañete, Álvaro; Pavez, Lynda; Pérez-Sanhueza, Alberto; Günther, Germán; Szreder, Tomasz; De la Fuente, Julio R.

Abstract

The photoreduction by amines and N-phenyl-glycine, NPG, of six styrylquinoxalin-2(1H)-ones derivatives substituted in the styryl moiety, R-SQ was studied by using flash photolysis. The photoreaction is initiated via a single electron transfer from the electron donor (amines or NPG) to R-SQ excited triplet state, R-3-SQ*, with the formation of a triplet state radical ion pair or a charge transfer exciplex, (3)[CRIP/CTE]. These species live longer than the respective R-3-SQ* and have very similar transient spectra. In the presence of NPG, these (3)[CRIP/CTE] evolve on mu s time scale to the respective hydrogenated radicals, R-SQH(center dot), whose transient spectra and reaction rate constants with NPG are reported. The identity of these hydrogenated radicals was supported by the spectra obtained with the alpha-H donor triethylamine and previous pulse radiolysis studies in 2-propanol. Our findings allow proposing a radical chain reaction mechanism that explains the observed spectral behavior and rationalizes formation of the main product formed by binding of four PhNHCH2 center dot derived from NPG decarboxylation.

Más información

Título según WOS: Spectral and Kinetic Study of 3-Styrylquinoxalin-2(1H)-ones Photoreduced by N-Phenylglycine and Amines
Título según SCOPUS: Spectral and Kinetic Study of 3-Styrylquinoxalin-2(1 H)-ones Photoreduced by N-Phenylglycine and Amines
Título de la Revista: JOURNAL OF PHYSICAL CHEMISTRY B
Volumen: 123
Número: 17
Editorial: AMER CHEMICAL SOC
Fecha de publicación: 2019
Página de inicio: 3688
Página final: 3698
Idioma: English
DOI:

10.1021/acs.jpcb.9b01950

Notas: ISI, SCOPUS